The cost of child welfare services in the U.S. has been estimated at $20 billion per year. During the past decade the number of teenagers in foster care has nearly doubled. Numerous studies have documented that these adolescents are at high-risk for developing serious problems, including substance use, participation in health-risking sexual behaviors, involvement in the juvenile justice system, serious educational problems and school drop-out, failed placements/foster care "drift," and homelessness. Yet, there is little research on the characteristics of interventions that can be used to guide the improvement of services for this vulnerable population of youngsters. The proposed study extends our previous research with adolescents referred for serious behavioral and emotional problems and research with elementary-aged children in foster care to a test of the efficacy of a preventive intervention for adolescents placed with foster and kin care providers in the San Diego County Child Welfare System. Two hundred and forty adolescents and their foster/kin care providers will participate (i.e., 60 in a foster/kin parent training only condition, 60 in a parent training plus youth skill training condition, and 120 in a casework "as usual" control condition). In addition to testing the efficacy of the two levels of intervention, we propose to examine the effects of the intervention on a set of parenting and youth variables that are expected to mediate the level of change on proximal and longer-term youth behavioral and health-related outcomes. Parenting mediators to be tested include positive parenting, parental supervision, and non-harsh discipline. Youth mediators are social competence, commitment to school, and knowledge about norms related to health-risking behaviors including substance use and high- risk sexual behavior. In addition, theoretical hypotheses about the effects of early risk/adversity factors to youth outcomes will be examined, and an economic analysis will be conducted to examine the relative benefits and costs associated with the two levels of intervention.